I received a coupon in the mail for a discount oil...

I received a coupon in the mail for a discount oil change on the car I bought from Future Ford, a 2012 Toyota Prius. I called and made an appointment 10 days in advance and advised that I was using the coupon received in the mail. When I arrived for my appointment, the service tech asked me who it was that set my appointment because he had nothing on the books. Plus, he had no oil filter or the special tool required to change the oil on a Prius. I was asked to come back the following day and they would complete my oil change. When I came back, they still did not have the tool to remove the old oil filter. They claimed they would obtain one and asked me to come back a third day in a row for the completion of my oil change. When it was finally completed, the tech advised me that the coupon did not apply to my vehicle because it was not a Ford. The coupons said nothing about the requirement that the vehicle was a fort, and I was asked to call to pay $20 more than the coupon amount.